Redox Reactions of a Stable Dialkylphosphinyl Radical

A stable
dialkylphosphinyl radical, 2,2,5,5-tatrakis­(trimethylsilyl)-1-phosphacyclopentan-1-yl (RH2P•), showed both irreversible one-electron oxidation
and reduction peaks at −0.24 and −2.29 V vs ferrocene/ferrocenium
couple. One-electron reduction of RH2P• with KC8 in the presence of 18-crown-6 (18-c-6) or [2.2.2]­cryptand
(crypt-222) gave the corresponding phosphides [K­(18-c-6)]+[RH2P]− and [K­(crypt-222)]+[RH2P]−. Whereas [K­(18-c-6)]+[RH2P]− exists as
a contact ion pair, [K­(crypt-222)]+[RH2P]− exists as a solvent-separated ion pair in the
solid state. Reaction of RH2P• with AgOTf afforded an unexpected product, a silver­(I) phosphaalkene
complex.

一种稳定的二烷基膦基自由基（dialkylphosphinyl radical）——2,2,5,5-四(三甲基硅基)-1-磷杂环戊烷-1-基（RH₂P•），在相对于二茂铁/二茂鎓电对的电势下，于−0.24 V和−2.29 V处分别表现出不可逆的单电子氧化峰与还原峰。将RH₂P•与KC8在18-冠-6（18-c-6）或[2.2.2]穴醚（crypt-222）存在下进行单电子还原，可得到对应磷化物[K(18-c-6)]⁺[RH₂P]⁻与[K(crypt-222)]⁺[RH₂P]⁻。其中[K(18-c-6)]⁺[RH₂P]⁻以接触离子对形式存在，而[K(crypt-222)]⁺[RH₂P]⁻在固态下以溶剂分离离子对形式存在。RH₂P•与三氟甲磺酸银（AgOTf）的反应可得到一种意外产物：银(I)膦烯配合物。